Synthesis of 13C-enriched benzo(a)pyrene derivatives, specifically those with 90% 15C label at the 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 position. Each derivative will have the label at one of these positions. Labelled arene oxides will be synthesized with the label at either one of the oxide carbon atoms. Selectivity studies of the reactions of carcinogenic electrophiles with biomolecules. Application of 13C NMR to studies of the products of the reaction of carcinogens with biomolecules. Evaluation of the sensitivity of 13C NMR for metabolism studies. Synthesis of substrates for the generation of benzo(a)pyrenylmethyl cations in the bay region and certain non-bay regions, and the determination of kinetics of such cations with biomolecules. Studies of the dye catalyzed singlet oxygen photooxidation of benzo(a)pyrene.